1. Field of the Invention
This specification relates to a magnetic switch capable of controlling power supply with being employed in an electric vehicle or the like.
2. Background of the Invention
In general, a magnetic switch is installed between a battery and an electric power converter(inverter) in electric vehicles or the like, such as hybrid vehicles, fuel cell vehicles, electric golf carts and electric folk lifts, for supplying or break the electric power supply from the battery to the electric power converter.
The magnetic switch comprises a movable contact contactable with or separated from a stationary contact, and an electromagnetic actuator to actuate the movable contact. The related art electromagnetic actuator comprises a coil, a stationary core, a movable core, a shaft, a return spring and a contact spring.
One of important factors which determine the performance of the magnetic switch is a contact pressure distance of a movable contact connected to the movable core and movable to a closing position contacting a corresponding stationary contact connected to the stationary core or an opening position separating from the stationary contact. The contact pressure distance corresponds to a value obtained by subtracting a contact distance between the stationary contact and the movable contact on the opening position from a movable distance of the movable core. However, in the related art magnetic switch, the contact pressure distance may be affected directly by the deviation of the movable distance or the contact distance. For example, with the same contact distance, if the movable distance increases by 0.1 mm due to a defective welding of a shaft of the movable core, the contact pressure distance further increases by 0.1 mm. Similarly, with the same movable distance, if the contact distance decreases by 0.1 mm because the stationary contact is installed 0.1 mm closer to the movable contact, the contact pressure distance further increases by 0.1 mm.
In general, the movable distance of the movable contact is within 2 mm, and in this case, the contact pressure distance should be controlled within 0.1 mm. However, as aforementioned, in the related art magnetic switch, when the deviation of the movable distance or the contact distance is generated due to an assembly tolerance of the movable core, the shaft and the stationary contact, it may immediately affect the contact pressure distance, which results in the deviation over the performance of the magnetic switch.